According to their constructions, touch panels may be classified into add-on touch panels, on-cell touch panels and in-cell touch panels. For an in-cell touch panel, touch electrodes of the touch panel are disposed inside the liquid crystal display, which can reduce the overall thickness of the assembly, and also drastically reduce the manufacturing costs of the touch panel. According to the operation principles, touch panels may be classified into resistive touch panels and capacitive touch panels. Capacitive touch panel supports multipoint touch function, has high light transmittance and low overall power consumption, high touch surface stiffness and long service life.
At present, a capacitive in-cell touch panel is implemented by directly adding touch scan lines and touch sensing lines on the array substrate, that is, two layers of strip electrodes crossing each other in different planes are manufactured on the surface of the array substrate, serving as touch driving lines and touch sensing lines of the touch panel respectively and mutual capacitance is generated at intersections of two electrodes in different planes. It operation process is as follows: the voltage signals coupled out by touch sensing lines via mutual capacitance are detected when touch driving signals are applied to electrodes serving as touch driving lines. In this process, when a human body such as a finger contacts the touch panel, since the human body is a conductor, coupling capacitance is generated between an electrode as a touch driving line and an electrode as a touch sensing line, which acts on the mutual capacitance to change the capacitance value of the mutual capacitance near the touch point, and in turn changes the voltage signal coupled out by the touch sensing line. It is possible to determine the position of the touch point according to the change of the voltage signal.